EFFECTS OF BONE MORPHOGENETIC PROTEIN-2 ON HUMAN NEONATAL CALVARIA CELL-DIFFERENTIATION

Citation
E. Hay et al., EFFECTS OF BONE MORPHOGENETIC PROTEIN-2 ON HUMAN NEONATAL CALVARIA CELL-DIFFERENTIATION, Journal of cellular biochemistry, 72(1), 1999, pp. 81-93
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology,"Cell Biology
ISSN journal
0730-2312
Volume
72
Issue
1
Year of publication
1999
Pages
81 - 93
Database
ISI
SICI code
0730-2312(1999)72:1<81:EOBMPO>2.0.ZU;2-D
Abstract
Bone morphogenetic proteins (BMPs) are factors that promote osteoblast ic cell differentiation and osteogenesis. It is unknown whether BMPs m ay act on human osteoblastic cells by increasing immature cell growth and/or differentiation. We investigated the short- and long-term effec ts of recombinant human (rh)BMP-2 on cell growth and osteoblast phenot ype in a new model of human neonatal pre-osteoblastic calvaria cells ( HNC). In short-term culture, rhBMP-2 (20-100 ng/ml) inhibited DNA synt hesis and increased alkaline phosphatase (ALP) activity without affect ing osteocalcin (OC) production. When cultured for 3 weeks in the pres ence of ascorbic acid and inorganic phosphate to induce cell different iation, HNC cells initially proliferated, type 1 collagen mRNA and pro tein levels rose, and then decreased, whereas OC mRNA and protein leve ls, and calcium accumulation into the extracellular matrix increased a t 2 to 3 weeks. A transient treatment with rhBMP-2 (50 ng/ml) for 1 to 7 days which affected immature HNC cells, decreased cell growth, incr eased ALP activity and mRNA, and induced cells to express ALP, osteopo ntin, and OC at 7 days, as shown by immunocytochemistry. At 2 to 3 wee ks, matrix mineralization was markedly increased despite cessation of treatment, and although OC and Col 1 mRNA and protein levels were not changed. A continuous treatment with rhBMP-2 for 3 weeks which affecte d immature and mature cell reduced cell growth, increased ALP activity and mRNA at 1 week and increased OC mRNA and protein levels and calci um content in the matrix at 3 weeks, indicating complete osteoblast di fferentiation. These results indicate that the differentiating effects of BMP-2 on human neonatal calvaria are dependent on duration of expo sure. Although long-term exposure led to complete differentiation of O C-synthesizing osteoblasts, the primary effect of rhBMP-2 was to promo te osteoblast marker expression in immature cells, which was sufficien t to induce optimal matrix mineralization independently of cell growth and type 1 collagen expression. J. Cell. Biochem. 72:81-93, 1999. (C) 1999 Wiley-Liss, Inc.